This software seems VERY promising, but:

Is ORB safe?

It seems that ORB staff can access my whole PC... how is this protecting my files and data?

this is a quote:

You are correct in that the HTTP requests go through our servers, and there is not much we could do about it (short of requiring our users to host their own web servers for that purpose).

As for the streaming of audio, live TV, recorded TV, and video, you do not have to go through Orb servers. If you have a router with UPnP capability (most routers of these past 18 to 24 months do), you can enable that feature on your router and Orb will automatically detect it, enable DirectStream (Orb tray icon | Configuration | Advanced) on your Orb system, and from that moment on, send the streams directly from your home PC to the device you use to access your Orb media, thus bypassing Orb servers. You can actually verify that by looking at the streamed file's URL in your media player's file properties: you should then see your Orb PC IP address as the source (not Orb stream server).